The conventional optical system for flow cytometers includes a collecting lens to collect light from the interrogation zone, beam splitters to split the light into different channels based on wavelength, and several detector subsystems with filters to pass only particular wavelengths (such as 515-545 nm, 564-606 nm, and 653-669 nm).
To use the conventional optical system, the beam splitters and filters must be arranged in a very particular order (monotonically increasing or decreasing order). For example, a first beam splitter must split between the two lower frequency bands, a first detector subsystem must filter between the lowest frequency band, a second beam splitter must split between the two higher frequency bands, a second detector subsystem must filter between the middle frequency bands, and a third detector subsystem must filter between the highest frequency bands. To change the wavelength detection of the conventional optical system (for example, to replace the frequency band that is originally the highest with a frequency band that is now the lowest) would require the re-arrangement of the entire optical system (including swapping both filters and beam splitters). In other words, with a conventional optical system, the step of filtering the light of the first channel affects the light of the second channel.
Thus, the user must skillfully arrange the filters in a particular order or the detector subsystems will not function correctly. This limitation prevents the easy swapability of the filters and the easy modification of detection parameters. Further, the particular arrangement of the optical table decreases the reliability and the ruggedness of the flow cytometer since the alignment of the beam splitters affects the detection of each of the detector subsystems.
Thus, there is a need in the flow cytometer field to create a new and useful optical system. This invention provides such new and useful optical system.